Transmission and controls therefor



Oct. 14, 1952 H, w, GlLF|| AN 2,613,773

' TRANSMISSION AND CONTROLS THEREFOR Filed May 5, 1951 Y E 5. wf .-V// .ww HW wm Patented Oct. 14, 1952 TRANSMISSION AND CONTROLS THEREFO Henry W. Gilfillan, Detroit, Mich., assignor to Chrysler Corporation, Highland Park, Mich., a

corporation of Delaware Application May 5, 1951, serial No. 224,779

20 Claims.

This invention relates to a power transmission unit and controls therefor, the unit being particularly adapted for use as a reverse and reduction drive gear for a marine drive train installation.` This is ankimprovement on the copendingapplication of H. W. Gilfillan et al., Serial No. 213,522, filed March 2, 1951.

It is a primary object df,V this invention to provide a compact powertransmission gear box adapted for vuse asa reductionpand reverse gear unit'in a marine drive train installation wherein the forward and reverse drives are controlled by novel, electrically operated, clutch and brake means that insure smooth, vpractically instantaneous, shifts between the forward, neutral and reverse drive ratios.

Secondly, it is another object of this invention to provide a power transmission unit with controls therefor that may be easily and economically located at any point adjacent to or remote from the transmissionr gear box. Reversey and reduction gearing of the type herein disclosed has usually been operated by clutch and brake devices controlled by mechanical linkages or by hydraulically operated mechanisms and each of these types of controls has several rather obvious disadvantages. Mechanical linkages rapidly develop wear and free-play that often render the control mechanisms diilicult and slow to operate. In addition mechanical controls are expensive and they are alsordifiicult to'install at control stations remote from the power transmission unit. Hydraulic controls necessitate pressure uid pumps and valving that areA quite'expensive and subject to disruption due to foreign matter entering the control fluid. In addition the fluid conduits that must be run to the various control stations throughout the ship'y are diflicult to install and repair and they provide a constant source of possible failure which failure not only renders the control system inoperative but further has the danger of distributing the pressurized control fluid to various localities of the ship Where it might ignite i-lres or damage cargo stored aboard the ship. With the electrically operated transmission control system herein disclosed, conventional weatherproofed wiring may be easily and economically run fromV the transmission gear box to any number of control stations throughout the ship and the operation of the gear box controls.

does not require the shifting of mechanical linkages nor the transfer of pressurized fluid between 2 novel design and is arranged to be operated by inexpensive, reliable controls.

It is a further object of this invention to provide a power transmission unit having electrically operated brake means adapted to anchor the transmission driven shaft against rotation when the power transmission is in a no-drive or neutral condition, said neutral brake means being associated with the electrically operated controls for this transmission in such a manner that its operation is automatic with changes in the forward and reverse drives transmitted by this unit.

It is still another object of this invention to provide a simplified, improved, forward and reverse gear box having novel electromagnetically operated controls that include an improved type of drive transmitting armature unit and an imvarious locations about thership. Furthermore,

the electromagnetically operated armature'unit proved control circuit therefor. l n

It is still another object of this invention to associate an electrically operated split or double armature clutch and brake control mechanism with an engine throttlel control element such that modulated energizationkof the armature control circuit` insures smooth, speedy changes in the forward and `reverse drives transmitted.

Other objects and advantages of this invention will become readily apparent from a reading of the attached description of the invention and a consideration of the related drawings wherein:

Fig. 1 is a sectional elevational view of the power transmission unit embodying this .in-

y vention;

valong the line 3-3 of Fig. 1;

Fig. 4 is a fragmentary sectional elevational view of an alternate form of driven shaft end connection; and

Fig. 5 is a schematic view of the electrical control circuit from the power transmission unit disclosed in Fig. l.

The power transmission unit shown in Fig. 1 of the drawings comprises driving and driven shafts l0 and Il respectively, said'shafts being axiallyy aligned and journalled in theV housing unit Y |12. The bearing support for driving shaft l0 in housing l2 is not shown whereas the bearing support I3 for the driven shaft Il is clearly disclosed. The forward end of driven shaft Il is shown piloted within the rear end portion of driving shaft I0 by means of a bearing assembly I4. Encircling and extending between the ad- 'jjacent ends cf rheshafts lo, Il is adifferential 'one another (see Fig. 2 I several spoke elements 2E pierce the wall vof the 4carrier case2l and projectradially'outwardly 3 gear unit I5. Differential gear unit I5 comprises a pair of axially spaced apart side gear elements I6 and I'I respectively. Side gear element I6 is drivingly connected to the driving shaft I0 by means of the splined connection I8. Side gear element Il is connected to the driven shaft II by means of thel splined connection I9. Encircling the axially spaced side gears I6, I l and journalled thereon by means of the bearings is the drumlike differential carrier case 2|. Carrier case 2I is of a two-piece or split case construction wherein the two cup-like parts 2Ia.,y 2lb of the casing are held in assembled position by means of a plurality of bolt and nut'connections 22.

Mounted within the carrier case 2l and journ nalled on the forward end portion of the driven shaft II is a pinion gear support member 23. Pinion gear support member 23 comprises a hub compression spring elements 44. Spring elements 1M tend to continuously separate the armatures 30a and Silb and to lightly force the outer faces 33a" and 3Gb" of the armatures into engagement with the opposed faces of the coil elements 3,2 and 34 respectively. Thus due to the spr-ings t4 the armature plate 30a is normally in contact with the coil element 32 and the armature plate 30h is normally in contact with the coil element 34. Due to this spring pressed contact of the armature plates 38d and 30h with each of the coil elements 32 and 34, a closed magnetic circuit is always available on initiating energization of either of the coil elements 32 and 34. This closed f v`circuit insures a very fast acting clutch and brake portion 213 with a plurality of radially extending spoke elements projecting from the hub that journals'the several differential-pinion gears 25.

In the construction. herein disclosed the support member 23 has four spoke elements 25 which vspoke elements are arranged at right angles to The outer endsof the therebeyohd a sufficient distance to support the concentrically arranged double armature unit Bil.

The outer-'ends of spokcsfii provide stud fcrmations 28 that are adapted to be drivin'gly seated in' slotted formations 1235:@291) formedy in the inner peripheral edges offface-to-face arranged armature'members 33a,Y 33h respectively. The

connections 2S, 29a, 2919,4 between the support spokes 25'and the split armatures 39a. 33h permit axial shift of the armature plates 39a, 33h relative to the differential cas'ei.'

Each of the split or double armature velements Band 33h is a iiatvrir'ig-likey plate element as 'clearly kshown in Fig. 2;Y Formed along the inner 'peripheraledg'e of the armatures 33a and 33h are -thedrive transmitting, stud receiving, Vformations 23a and 2gb respectively. The inner vside faces 33av and 33h of the armatures' 33a and `33h i energization of the solenoid coil units 32 and 34 respectively. The outer faces Sia'" and 3819" of the armature plates that are adapted to be drawn into drive transmitting engagement with opposed side faces of the coil elements 32 and 33 respectively, are preferably roughened slightly to prevent slip between these engageable surfaces. Fig. 2 h'asthe outer faceb'" of armature disc 3th vhatched to indicate the slight surface roughening applied to this surface. It has been found that this initial roughening of the armature faces '30am and Stlb" eliminates the 4necessity of a run-in` period for the electromagnetic clutch and brake elementsv32 and 34 of this power transmission unit and thus theV transmission unit operates at peak eiciency during initial use and ,at all other times. While this slight roughening of the surfaces a and 30b" is not an absolute necessity, still, it has been found to be quite advantageous.

f The inner faces 30a' and 33h of the armatures 30a and 30o each have a number of depressed control for the transmission unit disclosed. The spring separated, split or double armatures 33a and 38h not only insure a fast acting transmission control system but in addition these double armatures provide a means for modulating the engagingv and disengaging action of the associated clutch and `-brake'devices. On initiating energization of coil'element'32 the armature plate 30a is in engagement with the opposed, inner side face of the coilelement 32 and a closed magnetic ycircuit is'available. Thus armature 33a and coil 32 willimmediately be held together with a relatively lightv force in addition to the force exerted by the springs 44. As the energization of the coil 32 increases the varmature plate 6I on the outer side of coil 32 v(to be described subsequently) will then be drawn into contact with ythe outer side face of the coil 32 and thus the electromagnetic circuit and the force engaging the armature 33a and coil 32 will be gradually increased. On further energization of the coil 'the other split or. double armature 30D will be landdisengaging action of the clutch and brake transmission control devices is automatic. While the action of the double armature has been explained with respect toonly energization of -coil 32, it is thought to be obvious that a like action will ytake place during energization of coil 33. On deenergizationof the coil element 32, after full energization, first the armature plate 33h will-be `releasedand forced back into engagement with the coil element 34 by the spring 44. Thereafter the electromagnetic circuits through the armature elements 6I and 30a will be reduced and a gradual deenergization and release of the drive transmitting connection between the armature 30a and coiljSZ will result. Due to the initial release of the armature'plate 30h on deenergization of the coil 32, it is apparent that armature 3012 will be in actual contact with the coil 34 before the coil 32 is completely deenergized so that if the coil r3ft is thereafter energized there always exists a closed electromagnetic circuit to initiate energization of either of coil elements 32 or 313. The operation of the double armature members a, 30h in this transmission unit will b'e more fully described subsequently.

In the construction herein disclosed the differcnt ial pinion gearl elements 26 are formed as combination bearing and gear elements wherein the outer race of the bearing element provides the pinion gear element that meshingly engages with and extends between the axially" spaced apart side gear elements I6, I'I. It is realized that other types of differential pinion gears than those herein disclosed may be utilized in a differential transmission gearing of the type herein disclosed without altering applicant/s invention in Vany way but this type of pinion gearing has bee found to be quite satisfactory. f

Encircling the differential carrier case EI and arranged on opposite sides of the armature mem- '.bers 30a, 3012 are a pair of electromagnetic coil elements 32 and 34 respectively. The coil elements 32 and 34 are each formed from a pair of spaced, concentrically arranged, magnetizable rings 32a, 321) and 34a, 341) respectively. Each pair of concentric rings are drivingly connected by non-magnetizable, circumferentially spaced, struts 33. Fixedly mounted between each pair of concentric rings 32a, 32h and 34a, 34h is a coil winding 39 and 5I resp-ectively. Eachof the outer rings 32h and 34h include means around their outer peripheral surfaces whereby the coil elements may be supported in predetermined positions within the housing I2. Coil ring 32h is fixedly connected to the housing I2 by means of the peripheral flange formation 35 that is connected to housing I2 by the bolt and nut connectors 36. an opening 31 that receives av conductor element 38 adapted to connect the coil winding 39 of coil element 32 to a suitable electrical source.

The coil ring 34h has a step formation 4I in its outer peripheral surface that receives a ring element 42. Ring element 42 is connectedv to the coil ring 3417 by means of screw connectors such as the connector 43. Ring 42 is supported by and connected to a spider element 4'5 'by means of bolt connections 46. Hub element 4`I of the spider element 45 is drivingly connected to the driven shaft I I by means of the splined connection 48. Spider element 45 has suitably mounted therein conductor elements 49 that are adapted to transmit electrical energy from a suitable supply source to the coil winding 5I of the coil element 34. As spider element 45 is rotatable, a suitable slip ring connection 52 is provided between the fixed electrical contacts 53 and the rotatable conductors 49. The leads 55 for the fixed contacts 53 may be supported in a transmission case sleeve 54 or anchored in position within housing I2 in any other suitable manner.

Encircling the carrier case 2I of the differential gear unit I5 and arranged on the outer sides of the coil elements 32 and 34 are a pair of armature membersri and 6 2 respectively. The

armature members- 6I and 62 are drivingly connected to the carrier case 2I by means of drive pin connections such as the pins 63. Armature elements 6I and B2 4are axially shiftable along the carrier case 2| due to the looseness of the pin connections 63.'

Drive is transmitted through this power mission unit in the following manner: v y

If the driven shaft I I is to be driven forwardly, that is in the same direction as the driving shaft I0, then the electromagnetic clutch element 34 is energized and the electromagnetic brake element 32 is deenergized whereby the armature members trans- Flange formation 35 is pierced by 30h andZ will .be drawn into drive transmitting frictionalengagement with'. the opposite side surfaces of the coil member34 such that the carrier case Z'Iand the drven'shaft II will be drivingly locked together. `With the carrier'case 2l xed to the driven shaft II, the differential gearing I6, 26, I1 is lockedin a fixed condition and drive is transmitted directly from the driving shaft I0 to the driven shaft II at a 1 to 1 ratio. If reverse drive is to be transmitted through the gear box, that is drive of the driven shaft Il ina direction opposite to that of the drive shaft I0, then the electromagnetic brake 32 is energized and the electromagnetic clutch element 34 is deenergized whereby the armature elements 6I and 30a are drawn into drive transmitting frictional engagement with the opposite side surfaces of the fixed brake element 32. Engagement of the armature member 30a with the fixed brake element 32. anchors the differential carrier case2I against rotartion. yWith the carrier case 2'I anchored to the housing I2 by brake 32 then rotation of the driving side gear vI6 will cause the pinion gear elements 26 to rotate in such a manner that the driven sidegear I'Iwill be rotated inja direction opposite to that of the driving side gear I6. As side' gears IB,. I1 `are xedly connectedto their respective 'shafts I0, II, it is obviousthat the driven shaft I'I will be driven in a direction opposite to that of the driving shaft IIJ.1

Input to the driving shaft I0 may be directly from an engine crankshaft or through gearing (not shown) that is'meshingly engaged with the pinion gear element 'II that is keyed to the driving shaft I0 as at 12. The output from driven shaft I I may be transmitted to a nal drive element (not shown) through reduction gearing (not shown) that is meshingly engaged with the driven lpinion 'I3 that is splined to the rear' end portion of driven shaft I I by the connection 14. If direct drive from the driven shaft II to a -nal drive element such as a prop shaft or thelike is desired, then a, flanged connection such as that shownv at 'I5 in Fig.3 may be -splined to the driven shaft II to provide means 'to directly connect driven shaft II to the nal drive member to be driven thereby. f

Marine reversing gearing of the general type herein disclosed has been plagued by a -phenomena that is very objectionable and often causes serious trouble. This phenomena results from the fact that when the power Itransmission gearing is established in a neutral or no-drive condition, there is a broken drive trainbetween the driving and driven shafts that will permit the driven shaft I I to rotate freely in either direc'- tion. Accordingly, if the transmission is moved from a forward or reverse drive transmitting condition to the neutral position the passage of water through the associated propeller shaft, as the boat glides through the water, is suicient to keep the propeller shaft rotating and frequently the rotating propellerv will foul lines, fish nets and other gear located beneath the vessel. An even more serious consequence of the fact that there is a broken drive connection between the driving land driven shafts when the transmission gearing is arranged in a neutral or rio-drive condition, results from the fact that friction within the gear unit I5 may be sufficient to cause the differential gearing to transmit some drive between 'the driving and driven shafts I0, I I even though the electrically operated clutch and brake devices 32, 34 of the transmission gearing are in a deenergized condition. As a result, if the transmission is in neutral and the engine is idling or being raced to warm it up, there is danger that the propeller shaft will rotate and the ship may. moveeither forwardly or in a reverse `direction unless it is suitably anchored at the time. `'This undesired movement of the vessel due to the friction of the differential gearing-transmitting. drive can frequently cause damage to the vessel `and/or to fishing 'gear or structures located adjacent to or beneath the vessel at the time of the unintended movement. Y The -invention herein disclosed provides a means for eliminating any undesired movement of the driven shaft whenever the transmission gearing is in a no-drive or neutral condition. Unintended rotation of the -driven shaft is prevented by means of the electrically operated brake mechanism 80 that :is adapted to be frictionally engaged with a `side surface of the spider element 45 whenever the transmission is conditioned for neutral or no-drive. Brake mechanism comprises an electromagnetic coil element 8|, similar in construction .to coil elements 32 and 34, that has a side surface'82 that is normally maintained inlight'frictional engagement with the surface portion a Vof the spider element 45. VCoil ring 8| Vis supported from the transmission housing l2 by means of a plurality of stud bolts 83\(only one shown). Bolts 83 have their threaded ends connected into the housing |2 so as to lockthe bearing elements I3 in position `in the housing ,|2. The head ends of the bolts 83 are provided with axially extending stud-like formations 85 that seat in bores 86 in the coil ring 8| so as to anchor the coil ring 8| against rotation. Stud portions 85 of bolts 83 mount `compression springs 81 that normally urge the coil ring 8| vinto light frictional engagement with the surface portion 45a. of the spider 45. Conductors 89 that connect the coil winding 89of coil ring 8| to a suitable source of electrical energy may be housed within the housing sleeve 54 in the same manner as previously described'with regard to the conductors for the slip ring device 52, 53.

The control cir-cuit for the several electromagnetically operated clutch and brake units associated with this transmission isschematically shown in Fig. 5. In this circuit-diagram the battery or other source of electrical energy 92 is grounded at 93. Energy source 92 is connected to the energy supply terminal 94 through the series arranged ignition switch 95, fuse 96 and ammeter 91. Energy supply'terminal 94 is connected by a branch circuit lead9| 'to a rheostat device that includes pivotally mounted rheostat arm 98 that is adaptedto swing across the resistance element 99 of the rheostat unit to vary the circuit resistance and thereby control the current flow to the conductor |00. The movement of the rheostat control arm 98 is controlled by the engine throttle control pedal or lever |0|. Throttle control-|0l is pivotally mounted at |02 and is fixedly connected by the link |03 to the rheostat arm 98. Link |03 also mounts the switch contact |04 on its lower end. The conductor |00, that is arranged to transmit current from the rheostat unit to the coil windings 39 and 5|, is connected to a contact element |06 carried by the pivotally mounted transmission drive control lever |'01. Lever |01 is an insulated element mounted to swing about the pivot point |08 so that it may assume the three positions R, N and F which indicate respectively the reverse, neutral and forward control positions of the transmission unit. Contact |06 is adapted to selectively engage the resistances and ||2 of a second rheostat device as the transmission control lever |01is swung from the neutral position to the drive transmitting forward and reverse positions respectively. When lever |01 is in the neutral position the contact |06 is not engaged with either of the resistances or ||2 and the circuit through conductor |00 is broken. Resistances and ||2 are connected by the conductors ||3 and v|| 4 to the forward clutch coil winding 5| and the reverse brake coil winding 39 respectively. From Fig..5 it is obvious that movement of the transmission control lever |01 from the neutral to either o'f the forward or reverse drive transmitting positions gradually reduces the resistance in the energy supply circuit to clutch and brake devices 32, 34. The clutch and brake coil windings 5| and 39 are grounded at ||5 and H6 respectively.

The energy supply terminal 94 is also connected by the parallelly arranged branch circuit lead |09 to one of the pair of spaced contacts ||1. The other of the contacts ||1 is connected to a conductor |18. Conductor H8 is connected to a second contact ||9 that is carried by the pivotally mounted, insulated, transmission control lever |0'|. Contact 9 is adapted to be selectively engaged with the contact bar elements |2| or |22 as lever |01 is swung between forward and reverse positions. As was the case with contact |06, the contact ||9 does not engage a conductor element when the transmission control lever is in the neutral position and thus the circuit through the conductor ||8 is always broken when the transmission control lever |01 is in the neutral position.

Energy supply terminal 94 is also connected by the parallelly arranged branch circuit conductor ||0 to a conductor |25 that is adapted to directly transmit current from the supply source 92 to the neutral brake coil winding 89 whenever the control llever |01 is in the neutral position. Neutral brake coil winding 89 is grounded at |9I. To prevent transmission of current to the neutral brake coil winding 89 at times v vkhen the lever |01 is in other than the neutral position, a separate pivotally mounted switch lever |21 is utilized. kLever 21 is pivotally mounted at |28 so as to swing in an arc similar to that of the transmission control lever |01. Lever 21 is connected to the lever |01 by the rigid link |29 such that levers |01 and |21 move in unison. Mounted on the lever |21 is a contact element |3l' that is connected to the conductor |25. Contact |3| is arranged to engage the contact element |32 whenever transmission control lever |01 is in the neutral position, Contact |32 is connected to the neutral brake coil winding 89 by the conductor |33.

Ifthe transmission control lever |91 is positioned in the neutral position as indicated in Fig. 5, it will be noted that the circuit from the battery 92 through the rheostat control arm 99, resistance 99 and conductor |00 is broken due to the fact that the contact |06, carried by the insulated lever |01, is out of contact with each of the resistances and 2. Accordingly, whenever the transmission control lever |91 is in the neutral or no-drive position electrical energy cannot be supplied to either of the conductors l I3 and ||4 and thus neither the forward clutch 34 nor the reverse brake 32 is operative vfor the transmission of drive between the driving and driven shafts l0, Furthermore, whenthe throttle control pedal will never cause the transmission of drive through the gear box even though the accelerator pedal |0| might be depressed to such a degree that-the contact |04 is engaged with the contacts Ill. If contacts |04 and ||1 are engaged by the depression of accelerator pedal |0|, while drive control lever |01 is in the `neutral position, then the conductor I8 transmits current to the contact I9 but contact ||9 will not be engaged with either of the conductor contacts |2| or |22 when transmission control lever |01 is in the neutral position. Thus there is no means for energizing the brake or clutch 32, 34 and thus no means for transmitting a drive through the gear box when the lever |01 is in the neutral position regardless of the condition of the throttle control l0 At closed throttle it w-ill be noted that energy is delivered to the conductor |00 through the resistance 99. On initial movementof the transmission drive control lever |01 into either a forward or reverse control position, the contact |00 carried by the drive control lever |01 is moved along one of the resistances or |2 and the amount of resistance in the circuit is gradually diminished such that the current supplied to the coil windings and 89 is gradually increased to thereby gradually energizethe coil windings 39 or 5|. This gradual energization of the coil windings 39 or 5| causes a feathered or modulated engagement of the associated armature elements a, 30h with the coil elements 34, 32 in the manner previously described. Thus it will be seen that the mere movement of the transmission drive control lever |01 from its neutral position to either its forward or reverse position produces a modulated engagement of the associated clutch or brake device 34, 32.

After the transmission control lever |01;,has

been moved into its selected forward or reverse position, subsequent depression of the throttle control lever |0| will further modulate or feather the action of the associated clutch or brake elements 34, 32 respectively, due to the fact that the throttle control lever |0| is directly connected to the rheostat control arm 98. Depression of throttle control lever |0 I swings the rheostat control lever 98 across the resistance element 99 and gradually cuts out the resistance 99 in the circuit to the conductor |00. The electromagnetic forces urging the armature units 30a, 30h into engagement with the associated devices 34 or 32 are thus gradually increased" in intensity as the throttle is depressed and thus the torque transmitting capacity. of the clutch 34 and the holding capacity of the brake 32 are-proportional to the load applied thereto'. `When the throttle lever |0| has been depressed to about one-quarter (M1) or one third (1/3) of its-throttle opening movement the contact |04, 4carried by' the throttle control lever |0'I,.will be engaged vwith the contacts and atthis time the .circuit through ductor ||8. If the drive control lever |01-is ina drive transmitting position when conductor ,il 8 becomes active for the transmission of electricall as, one quarter (1A) or one third (1/3) of throttle opening movement, then the` electromagnetic circuits for the clutch and brake 32, 34 maybe selectively energized and a substantially positive r drive can be transmitted between the driving and driven shafts I0, H.

The control circuit shown in Fig. 5 is particularly advantageous for trolling :operations and the like due to the fact that the transmission control lever |01 can be moved into its forward. drive position and at this time the clutch will be engaged and heldby an electromagnetic force that is sufficient tol transmitthe very low speed drive required for trolling operations. During trolling the throttle control lever |0| ismerely depressed the required amount to establish the. necessary trolling'speedand thereafter further operation of the throttle control |0| isunnecessary. f 1

Whenever it is desired to shift fromy forward to reverse during maneuvering, the normal operation of releasing the throttle 'control |0I cuts out the circuit through the conductor ||8 and theref after the effective controll circuitis through-the series arranged resistances 99 and.||| or .||2. Movement of the drive control lever |01 then gradually increases the resistance in the circuit being deenergized and thereafter gradually-reduces the resistance inthe circuit being. energized, This resistance control of the electromagnetic circuits insures smooth fast` changes in drive transmission.r Furthermore,l at the time that the drive control lever |01' moves into its centrally located neutral position between the forward and conduit |00-is shortcircuited and electrical energy l is now'appliedfromlthe:terminal 94 to the conreverse positions, the neutral brake 80 is applied and this anchorsthe driven shaft so that. the subsequent engagementv of theclutch or brake 34, 32 will be very smooth due to the fact .that the driven shaft has been.` braked between the time that it is reversed in direction. It is vthought that the above description of the'operation of this transmission points out the several advantages'of this novel transmission. control system.

The power transmission-unit hereinabove described is arranged to be controlled `by electrically operated means that require a continuous Vsource of electrical energy. To prevent the power transe mission unit from being inoperative whenA there might be a failure in the Apower supplyl source, this transmission also includes means whereby an auxiliary, mechanical, vpositive clutchfdevice |40 may be manually operated to drivinglyconnect the driving and driven' shafts |0,.|.|Tirre. spective of the condition of the electrical controls for the power transmission unit. `The manually operable mechanical clutch y |40 comprises.. :a toothed sleeve |4.| splinedtothe drivingl shaftl at |42 and shiftable 'axiallyualongthe driving shaft I0. The teeth |413;of sleeve Miara adapted to be moved into andout offengagement'with teeth |44 formed around :thevperiphery' 'ofyan opening inthe sidewall ofthe carrier case 2|.

When the teeth .|43 of sleeve 4| are engaged with the teeth v|44r f carrier case 2| then driving shaftI and carrier casel 2| are locked together in such a manner thatthe differential gearing I6, 26,' |1,` becomes a unitarystructure and transdirect drive' from the drive shaft to the drivenshaft ||.l The-clutch device |40 is the mechanical equivalent of the electromagnetically operated clutch 34 and thus this transmission includes two means whereby direct drive may be transmitted between the shafts I0, one means being'. the mechanical clutch |40 and the other means the electromagnetically controlled clutch 34.5: s

Actuation of the toothed clutch sleeve |4| is controlled by the movement of the clutch operating lever |48. Lever. |46 is pivoted at |41 to an ear |48 carried by the transmission housing l2. The free end |49 of lever |46 is positioned in a groove |50 formed in the sleeve |4| such that sleeve |4l may rotate relative to the lever4 end |49. The. pivoted end of lever |46 has a portionv |5,| arranged to be engaged by the threaded end of a set screw |52 which screw is threadably mounted in the transmission housing l2. Normally the set screw |52 is threaded into the housing to such a degree that the pivoted lever |46 is held in the position shown in Fig. 1. Set screw |52 is maintained in this position by means of the anchor wire |53 that is 'connected between an anchor device |54 and the head of the set screw, |52. Resilient means such as the spring- |55 is compressed between the housing Wall |48 and the clutch operating lever |46 such that on release ofthe set screw: |52 the spring |55 will swing the operating lever |46 counterclockwise about its pivot point. |41 andY thereby move the toothed sleeve |4| into engagement with the teeth |44 cf the carrier. case 2|; Due, tothe availability of the positive, clutch mechanism |40, it always is possible to transmit drive between the shafts I and |2 even though. the electrical system for conf.

trolling the several electromagnetic clutches and brakes 32, 3 4, 80 might be inoperative. Euther-l more, as the. clutch device |40r can be utilized to positively connect the drivingand driven shafts I0, it is possible; to start the engine unit associated with thispower transmissionr device by means: of pullingthe vessel through the water andcausing thev propeller toA drive the engine and tothus causeflring of the engine even though the electrical systemmight be dead. The incorporation of a positive safety clutch such` asa clutch |40.in.an electrically operated power transmis, sion unit of the` type herein described is conside. ered to, be a very, definiteimprovementin mech-1 anisms of the type herein described. It will be noted that the. positive clutch device 00, may be simultaneously engaged duringengagement of thetelectromagnetically operated clutch 34 to pre-f ventslip of the clutch Y34, or it may be separately operated when the clutch 34, is inoperative.

Ivelaim:

1. I-n a transmission comprising a housing jour-A nallinga pair of` axiallyaligned driving andi driven shafts, a differential gear set connected: between said shafts comprising a carrier case containing said gear set extending between and mounted for rotation relative to said shafts, a side gear. drivingly mounted on each of said driving and driven shafts, said side gears being arranged in spaced apart, opposed relationship within said carrier case,` pinion gearing journalled in saidV carrier. caseand arranged to extend between and. meshinglyengagefsaid side gears, a'y

first pair ofrarmatlres arranged concentrically about the central portion :of said carriercase in of armatures being arranged onopposite sides of' said rst pair of armatures, an electromagnetic brake element ixedto said housing having .pore tions arranged between la pair of said 'rst and second armatures, energization of' said brake ele. ment being effective'to engage said rbralrev por-A tions and a pair of said. firstand second armatures to anchor 'said carrier 'casete` said housing to provide means for the drive of said driven shaft in ra-direction opposite to that of 'said drive ing shaft, and an electromagnetic. clutch element. carried by said driven shaft havingrportions arranged between the other pair. of first and second armatures, energization or said clutch elementA being effective to engage said clutch portions and` said other pair of armaturesl to drivingly connect said carrier case and said drivenshaft to provide means for the drive of said. driven shaft in the same directionas said driving shaft.

2. In a transmission comprising a housing jour, nailing apair of aidallyy aligned drivingy and driv en shafts, a differential gear set connectedv be-I tween said shafts comprising a carrier case extending between andI rotatably mounted on said shaftsfa vside gear drivingly mountedon each of said driving and driven shafts, said side gearsV being arranged in spaced apart,v opposed rela.. tionship within said-carrier case, pinion gearing journalled in said` carrier Caseland arranged toy extend between and meshingfly engage said side gears, a pair of armatures arranged concentri'-, cally about saidcarrier case in' `fact-'i-.to-face rela-A tionship, saidy armatures each being.` drivingly connected to and shi-ftably mounted on said carrier case, an electromagnetic. brake elementxedz' to said hou-sing having.' portions` arranged adja. cent Aan outer surface of one. of said armatures, energization of saidbrake element being-effective to engagesaid brakeportions and said one armaturer to anchor saidcarrier. case' to sai'dhousing to provide meansv for Vthe` drive of" said` driveny shaftin a direction opposite-.to that of' sai'd drivingfshaft, and an electromagneticY clutch element carried by saidl driven shaftfhaving. portions ar-r ran-ged adjacent an .outer-.surface of the. otherarmature, energization:.of-.'said. clutch, element beingl effective to engage 'saidclutch `portionsandf said otherfarmature to. drivingly connect said carrier' lcase'andv said driven. shafttoJ provide. means for the drive ofsaidvdriven. shaft in the same direction assaid-drivin'g' shaft, andzresilient means normally urging' said. armatures apart to cause contact between the said '.brakeandf clutch portions and the adjacentlyfpositioneds arma-ture elements. y

3. In a. transmission comprising driving and driven shafts, differential-gearing; mounted on and connectible between said` slriaftstoy provide for the drive. ofi said'. driven. shaft; inopposite directions, said. gearing including; a gearing carrier` case. rotatably. mounted'A oni said shafts adapted to be selectively connected to said driven shaft and anchored' against rotation. to effect drive of the driven shaftinsaidiopposite direc,- tionsi a pair of annular. armature. lfzlatesL encircling.k said carrierucasel andi drivingly. connected thereto..r Said.Y armature-:plates being; relatively 13 movable in an axial direction and arranged in face-to-face relationship with resilient means normally urging the plates apart, an electromagnetic clutch element drivingly mounted on one of said shafts having portions arranged adjacent one of said armature plates and engageable therewith, an electromagnetic brake element fixedly supported relative to said carrier case having portions arranged adjacent the other of said mature plates are formed with minute depres-r sions. I

6. In a transmission as set forth in claim 3 wherein a manually operated, positive, mechan-l ical clutch device is provided between one of said shafts and said carrier case.

'7. In a transmission comprising driving and driven shafts, differential gearing mounted on and connectible between said shafts to provide for the drive of said driven shaft in opposite directions, said gearing including a gearing carrier case rotatably mounted on said shafts adapted to be selectively connected to said driven shaft and anchored againstrotation to effect drive of the driven shaft in said opposite directions, a pair of annular armature plates encircling said carrier case and drivingly connected thereto, said armature plates being relatively movable in an axial direction and arranged in face-to-face re lationship with resilient means normally urging theplates apart, yan electromagnetic clutch lelehaving portions arranged adjacent one of saidv armature plates and engageable therewith,afirst electromagnetic brake element fixedly supported relative to the carrier case having portions arranged adjacent the other of said armature plates to and .axially shiftableon said carrier case, aV

first electromagnetic brake element fixed to said housing having portions arranged adjacent a side surface of one of said armatures, energization of said brake element being effective to engage the said brake portions and said one armature to anchor said carrier case to said housing and provide means for the drive of said driven shaft in one direction, anv electromagnetic clutch element carried by said driven shaft having portions arranged adjacent a side surface of thev other of said armatures, energization of said clutch element being effective to engage said'- clutch portions and said other armature to drive ingly connect 4said carrier case and said driven shaft and provide means for the drive of said driven shaft in the opposite direction, and a second electromagnetic brake element fixed to said housing having portions arranged adjacent to and adapted to be engaged with portions of said driven shaft on energization of said second brake element to anchor -said driven shaft against rotation in either direction.

9. In a transmission comprising a housing journalling a pair of axially aligned driving and driven shafts, a differential gear seticonnected between said shafts comprising a carrier case extending between and rotatably mounted on said shafts, a side gear drivingly mounted on each of said driving and driven shafts, said side 'i gears vbeing arranged in spacedapart, opposed and engageable therewith, a second electroma'gnetic ybrake element xedly supported relative to said carrier case having portions arranged adjacent to and engageable with said carrier case, and an electrical control circuit for said electromagnetic clutch and brake elements including a transmission control lever operated switch' arranged to selectively effect energization and de-v energization of said clutch element and said first brake element, movement of said control levantov a position to deenergize either said clutch element or said first brake element automatically effecting energization of said second brake element. A

8. In a transmission comprising va housing journalling a pair of axially aligned driving and driven shafts, a differential gear set connected between said shafts comprising a carrier case extending between and rotatably mounted on said shafts, a side gear drivingly mounted on each of said driving and driven shafts, said side gears being arranged in spaced apart, opposed relationship within said carrier case, pinion gearing journalled in said carrier case and arranged to extend between and meshingly engage said side gears, a pair of armatures concentrically mounted about said carrier case having inner surfaces in face-to-face relationship, resilient means normally urging said inner armature `faces apart, each of said armatures being drivingly connectedl 0 ment drivingly mounted on one of said shafts '4` relationship within said carrier case, pinion gearing journalled in said carrier case and arranged to extend between and meshingly engage said side gears, a pair of armatures concentrically mounted about said carrier case having inner surfaces in face-to-face relationship, resilient means normally urging said inner armature faces apart,v each of said armatures being drivingly connected to and axially shiftable on said carrier case, a first electromagnetic brake element fixed to said housinghaving portions arranged adjacent a side surface of one of said armatures, energization of said brake element being effective to engage the said brake portions and said one armature to anchor said carrier case to said housing and provide means for the drive of said driven shaft in one direction, an electromagnetic clutch element carried by said driven shaft having portions arranged adjacent a side surface of the other of said armatures, energization of said` clutch element being effective tol engage said clutch portions and said other armature to drivingly connect said carrier case and said driven shaft and provide means for the drive of said driven shaft in the opposite direction,` a second electromagnetic brake element fixed to said housing having portions arranged adjacent to= and adapted to be engaged with portions of said' driven shaft on energization of said second brake element toanchor said driven shaft against rota-V tion in either direction, and an electrical control circuit for said electromagnetic clutch and brake elements comprising a transmission control lever operated switch to provide for the selective ener-v gization of said clutch element and said firstv brake element, said transmission control lever v afoifspvsf adapted to' be energized to provide for the drive of said driven shaft in one direction, an electroe magnetically operated brake 'associated 'with said gearing and adapted to be energized to provide for drive of said driven shaft` in the opposite direction, a drive control veler'nentv to 'provide .for selective energizatioii of the clutch and brake, and an electrical control circuit for said electr magnetically operated clutch and brake comprise' ing a source of electrical energy selectively Yconnectible by said drive control element to either said clutch or Said brake 'through a pair of par allelly arrangedbranch circuits, one Aof said branch circuits including a iirst rheostat device operatively connected 'to vs'aidthrottle Vvcontrol such that openingfthe throttle reduces the' resistance of the first rheostat device and -a transmise sion drive control element operated second "rheostat device in series with said iirst rheostat-device and arranged such that fnovement oi the drive control elever from a no-drive position to a drive transmitting position reduces the resistance of the second rheostatl device, the other of said parallelly arranged branch circuits including a switch operatively connected to said throttle con-v troland arranged I'suchfthat it is open at closed throttle and closed after a predeterminedopening of the throttle, closing of said switch short circuiting said one branch circuit and directly connecting the power Vsupply with the clutch or f the brake depending on the drive transmitting position of said drive control element.

11. In combination, anA engine driven power transmission unit including a drive shaft, a

gearing selectively connectible between said shafts to provide for drive of the driven shaft in opposite directions, an electromagnetically operated clutch connected to said gearing and adapted tobe energized to provide for the drive ofsaid driven shaft in one direction, a rst electromagnetically operated brake connected 'toisaid gearing, and adapted to be energized'to provide fori drive of said driven shaft in the opposite direction, a second electromagnetically operated brake 'connected to said gearing' and adapted to be energized to anchor said driven shaft against rotation, a transmission drive control lever to provide for selective energization o-f the clutch and the brakes, and an electrical control circuit for said electromagnetically operated clutch and brakes comprising a source of electrical energy selectively connectible oy saidY transmission drive control lever to either said clutch or said first brake 'through a pair of parallelly arranged branch circuits, one of said branch circuits including a rst rheostat device operativelyconnected to said throttle control such that opening the throttle reduces the resistance of the rst rheostat device and a transmission drive control lever operated second rheostat device in series with said rst rheostat device and arranged such that movement of the transmis sion drive control lever from a neutral position to a drive transmitting position reduces theY resistance of the second rheostat device, the other `of said parallelly'airanged branch circuits including a switch operatively connected to said throttle: control and arranged such that it is open at closed throttle and closed after 'a predetermined opening of the throttle, closing 'oi' saidswitch 'short circuiting saido'ne branch cir'-v cuitand directly connecting .the power supply' with thev preselected clutch or brake depending' on thepreselected. drive transmitting position Yor said transmission drive control lever, and a third bran'chcircuit connected in parallel with said pair of branch circuits connecting said source or electrical energy to said second brake, said third branch circuit including aswitch operatively connected .to said transmission drive control Alevei` such that said switch 'is closed only when said transmission drive control lever is in neutral position.` i. v

12.' In' combination, an engine driven power transmission unit including 'a drive shaft, a throttle control for the'engine, a driven shaft,

-gai'fig 'selectively colllctibl between Said shafts to provide for drive ofthe driven shaft in y`c g po`site directions, a 'first electrically operatedfdrive kcontrol unit associated with said gearing and adapted to be energized to provide for the drive of said driven shaft in one direction, a rsecond electrically operated drive controlfj'nit associated with said gearing and adapted 'to be energized to provide for drive of said driven shaft-in the opposite direction, atransmission drive control elementy to provide for selective v-eiiergization of the iirst and second drive-control units, and an electrical control circuit'ror saidy drive control units comprising a source of electrical energy selectively connectible by said transmission drive Vcontrol element to said drivecontrol units through a pair of parallelly arranged branch circuits, one of said branch circuits including a rstvariable resistance operatively 'connected to said throttle control such that, opening the 'throttle reduces the effective resistance 'of the rst variable resistance and a drive control elementjoperated second variable resistance in series With'said iirst variable resistance and arranged such that movement of the transmission drive control element from a nov-drive position' toY l'a drive transmitting .position reduces the resistance of the second variable resistance', the other of said parallelly arranged branch"y circuits including 'a switch operatively connectedto said throttle control and arranged suchA that it is open at 'closed throttle and closed afterva predetermined opening of the throttle, closing vof said switch short circuiting said one branch circuit and directly connecting the power supply with one of thedrive control units.

13'. In lconibinatior`i,' an engi-ne driven power transmission V'unit including a drive shaft, a throttle control for the engine, a driven shaft, gearingz yselectively connectible between said shafts. 'to lprovid'e for drive `of the driven vshaft in' opposite directions, a ir'st electrically operated .dri-ve Acontrol 'unit connected with said gearing 'and adapted to be energized to provide for the drive of said driven shaft in one direction,'.a (second electrically operated drive control connected wi'th said gearing and adaptedjto-be energized to .provide for drive of said driven shaft in the opposite direction, a third electrically 'operated drive control unit adaptedto -be energized toanchor said driven shaft against rotation, a transmission drive control eleinent to provide for .selective energicationof thedrive control units, and an electrical control circuit 'for said electrically operated drive control units' comprising a source of electrical energyv selectively Iconnecti-ble by said transmissionJ drive cont-rol` elements to said first and second drive control units through a pair of parallelly arranged branchv circuits, onel ofv said afinar/#73 17 branch circuits including a rst variable resistance operatively connected to said throttle control such that opening the throttle reduces Ithe resistance of the rst variable resistance and a vtransmission drive control element` operated second variable resistance in series with said first variable resistance and arranged such that movement of the transmission drive control element from va no-drive position to a drive transmitting position reduces the resistance of the second variable resistance, the other of said parallelly arranged branch circuits including a switch operatively connected to said throttle control and arranged such that it is open at closed throttle and closed after a predetermined opening of the throttle, closing of said switch short circuiting said one branch circuit and directly connecting the power supply ywith one of saidiirst or second drive control` units, and a third branch circuit arranged in parallel with the aforementioned pair of branch circuits and connected to said third drive control unit, said third branch circuit including a switch operatively connected to said transmission drive control element and arranged such that said switch is closed only when said drive control element is in a no-drive position.

14. In combination, an engine driven drivel shaft, an engine throttle control, a driven shaft, gearing selectively connectible between said shafts to provide for rotation of the driven shaft in vopposite directions, an electrically operated `clutch connected to said gearing adapted to be energized to provide for rotation of the driven shaft in one direction, an electrically operated brake connected to said gearing adap-ted to be energized to provide for rotation of the driven shaft in the opposite direction,` a drive control lever to provide for selective energization of the clutch and brake, and an electrical control vsystem forthe clutchand-brake comprising a'source of electrical energy connected by circuit means to said clutch and brake, said circuit means including a pair of parallelly arranged branch circuits connected to both said clutch and said brake, one branch circuit including a pair of variable resistances arranged in series having one of said resistances controlled by movement of the throttle control and the other of said resistances' controlled by movement of said drive control lever, the other of saidV branch circuits vincluding a normally open throttle control operated switch adapted to be. closed after a predetermined throttle opening.

15. In combination, an engine driven drive shaft, an engine throttle control, a driven shaft, gearing selectively connectible between said shafts to providefor rotation of the driven shaft in opposite directions, an electrically operated clutch unit connected to said gearing and adapted to be energized to provide for rotation of the rdriven shaft in one direction, a first electrically operated brake connected to said gearing adapted to be energized toy provide for rotation ofthe driven shaft in the opposite direction, a second electrically operated brake adapted to be energized to engagev and anchor said driven shaft against rotation, a drive control element for the gearing selectively positionable in forward drive, reverse drive and no-drive positions to respectively effect energization of the clutchand first and second brakes, and an electrical control circuit for the clutch and brakes comprising a, source of electrical energy conductor means to connect said source to said clutch and brakes. including a pair of parallelly arranged branch circuits, each of which is arranged to be connected .toboth said clutch and said first brake, one of said pair of branch circuits includinga pair of variable resistances arranged in series with one of said resistances controlled by the .opening and closing movement of the throttle control and the other of said resistances controlled by the movement of the drive control element between no-drive and drive transmitting positions, the other of said pair of branch circuits including a throttle control operated, normally open, switch that is closed after a predetermined throttle opening to provide a means for short circuiting said one branch circuit, and a third branch circuit arranged in par-v shafts to provide for drive of the drivenvshaft in opposite directions including a pair of armatures drivingly connected to said gearing and arranged to be selectively and cooperatively shifted between drive and no-drive transmitting positions by electrically operated means, an electromagnetically operated clutch connected to said gearing and adapted to beY energized to establish engagement with one of said armatures to provide for the drive of said driven shaft in one direction, a first electromagnetically operated brakev connected to said gearing and adapted to be energized to establish engagement with the other of said armatures to provide for ydrive of said driven shaft in the opposite direction, a second electromagnetically operated brake connected'to said gearing and adapted to be energized to establish a no-drive condition that anchors said driven shaft against rotation, a transmission drive control lever to provide for selective energization of the clutch and the brakes, and an electrical control circuit for said electromagnetically operated clutch and brakes comprising a source of electrical venergy selectively connectible by said transmission drive control lever to either said clutch or said first brake through a pair of parallelly arranged branch circuits, one of said'branch circuits including a first variable resistance unit operatively connected to said throttle control such that opening the throttle reduces the resistance of the rst resistance unit and a transmission drivev control lever operated second variable resistance unit in series with said first variable resistance unit and arranged such that movement of the transmission drive control lever from a no-drive position to a drive transmitting position reduces the resistance of the second resistance unit, the other of said parallelly arranged branch circuits including la first switch operatively connected to said throttle control and arranged such Ythat it is open at closed throttle rand closed after'a predetermined openingof .the

19 pair of branch circuits connecting said source` of electrical energy to said second brake, said third branch circuit including a, second switch operatively connected to said transmission drive control lever such that said second switchv is closed only when said transmission drive control lever is in the no-drive position.

17. An engine driven transmission adapted to transmit drive in opposite directions and to be 'conditioned'. for no-drive comprising a housing journalling a pair of axially aligned driving and driven shafts, a differential gear set connected between said shafts' comprising a carrier case extending -between and rotatably mounted on said shafts, a side gear drivingly mounted on each of said', driving and driven shafts, said side gears being arranged inspaced apart, opposed relationship withinsaid carrier case, pini-ongearng. journalledinsaid carrier'case and arranged to extend betweenand meshingly engage said side gears, a l

pair of armatures arranged concentrically about said carrier case in face-to-face relationship, said armatures each being drivingly connected to and shiftably mounted onsaid carrier case for aXial movement, an electromagnetic brake element fixed to said housing havingr portions arranged adjacent an outer surface of one -of said armatures, energization of said brake element being effective' to engage said brake portions and said one armature to anchor said carrier case to said housing to provide means for the drive of said driven shaft in a direction opposite to that of saidl driving shaft, andan electromagnetic clutch element, carried by said driven shaft having portions arranged, adjacent an outer surface of the other armature, energizationrof said clutch element being eective tov engage said clutch portions and said other armature to drivingly connect said carrier case and said driven shaft to provide means forl the drive of said. driven shaft in thesame direction assaid driving. shaft, resilient means normally urging said armatures aparti to cause light contact between the said brake and clutch portions and the adjacentlyv positioned armature elements, an engine throttle control, a` transmission drive control element, andan electrical control circuit for said clutch and. brake elements comprising a source of elec- 'trical energy selectively connectible by said transmission drive control element to either said clutchor said brake element through a pair of parallelly arranged branch circuits, one-of said branch circuits including a rst variable resistance device operatively connected to said throttle control such that opening the throttle reduces the resistance of the rst. resistance device and a, transmission drive control element operated second variable resistance device in series with said 'rst resistancedevice and arranged such thatl movement of thestransmission driveY control element from the no-drive position to a drive transmitting position reduces the resistance of the secondresistance device, the other of said parallelly arranged branch circuits including a switch operatively connected to said throttle control and arranged suchthat it is open at closed throttle and closed after a predetermined opening of the throttle, closing of said switch short circuiting said one branch circuit and directly connecting the power supply with one of the aforesaid clutch or thev brake elements depending on the drive transmitting position of said transmission drive control element.

18. An engine driven transmission adapted to transmit drive in either of two opposite directions 2() and to be conditioned for no-drive comprising a housing journalling a pair of axially aligned-driving and driven shafts, a diiferential gear set connected between said shafts comprising a carrier case extending between and rotatably mounted on said shafts, a side gear drivingly mountedcn each of said driving and driven shafts, saidv side gears being arranged in spaced apart, opposed relationship within said carrier case, pinion gearing journalledv in said carrier case and arranged to extend between and meshing-ly engage said side gears, a pair of armatures concentrically mounted about said carrier case having inner surfaces in face-to-face relationship, resilient means normally urging said inner armature faces apart, each of said armatures being drivingly connected to and axially shiftable on said carrier case, a rst electromagneticl brake element iixed to said housing having portions arranged adjacent a side surface of and normally engaged with one of said armatures, energization'of saidbrake element being effective to drivingly engage the said brake lportions and said one armature to anchor said carrier case to saidr housing and provide means for the drive of said driven shaft in one direction, an electromagnetic clutch element carried by said driven shaft having portions 'arranged adjacent to and normallyengaged with a side surface of the other of said armatures, energization of said clutch element being effective to drivingly engage said clutch portions and said other armature to drivingly connect said carrier case and said driven shaft and provide means for the drive of said driven shaft in the opposite direction, a second electromagnetic brake element fixed to said housing having portions arranged adjacent to and adapted to be engaged with portions of said driven shaft on energization of said second brake element to anchor said driven shaft against rotation in either direction and establish the rio-driveV condition, a transmission drive control element to'selectively control energizaticn of said clutch and brake elements, an engine throttle control, and an electrical control circuit for said electromagnetically operated clutch and brake elements comprising a source of electrical energy selectively' conneetible by said transmission drive control element to either said clutch or4 said rst brake element through a pair of parallelly arranged branch circuits, one of said branch circuits including a first variable resistance device operatively connected to said throttle control such that opening the throttle reduces the resistance of the first resistance device and a transmission drive control element operated secondvariable resistance vdevice in seriesk with said first resistance device and arranged such that movement of the transmission drive control element from a no-drive position to a drive transmitting position reduces the resistance of the second resistance device, theother of said parallelly arranged branch circuits including a first switch operatively connected to said throttle control and arranged such that it is open at closed throttle and closed after a predetermined opening of the throttle, closing ofsaid i-lrst switch short being effectiveto circuit said one branch circuit and directly connecting the power supply withthe preselected clutch or brake element depending on the preselected drive transmitting position of said transmission drive control element, and a third branch circuit connected in parallel with saidpair. of branch circuitsv andA arranged toconnect said source of electrical energy to said second brake element,

said third branch circuit including a second switch operatively connected to said transmission drive control element such that said second switch is closed only when said transmission drive control element is in the no-drive position.

19. In a forward and reverse drive gear mechanism, a support, a driving shaft and a driven shaft journaled in said support, differential gearing connected between said shafts comprising a gear carrier case encircling adjacent portions of said shafts and rotatably mounted relative thereto. a first pair of ring-like armatures encircling said carrier case and drivingly connected thereto so as to provide for movement of said firstpair of armatures axially of the carrier case, a second pair of ring-like armatures encircling said carrier case anddrivingly connected thereto, said second pair of armatures being arranged axially of said carrier case so as to be positioned on opposite sides of said ilrst pair of armatures, a first electro'- magnetic coil unit mounted on said support having portions thereof encircling said carrier case and positioned between one pair of said first and second armatures, a second electromagnetic coil unit mounted on one of said shafts having portions thereof encircling said carrier case and positioned between the other pair of said first and second armatures, and electrically operated control means to selectively activate the several coil units.

20. In a forward and reverse drive gear mechanism, a support. a driving shaft and a driven shaft journaled in said support, differentialgearing connected between said shafts comprising a gear carrier case encircling adjacent portions of said shafts and rotatably mounted relative thereto, a rst pair of ring-like armatures encircling said carrier case and drivingly connected thereto so as to provide for movement of said first pair of armatures axially of the carrier case, a

second pair of ring-like armatures encircling said carrier case and drivingly connected thereto, said second pair of armatures being arranged axially of said carrier case so as to be positioned on opposite sides of said first pair of armatures, a first electromagnetic coil unit mounted on said support having portions thereof encircling said carrier case and positioned between one pair of said rst and second armatures, a second electromagnetic coil unit mounted on one of said shafts having portions thereof encircling said carrier case and positioned between the other pair of said first and second armatures, a third electromagnetic coil unit mounted on said support having portions thereof engageable with armature portions carried by one of said shafts, and electrically operated control means to selectively activate the several coil units.

HENRY W. GILFILLAN.

REFERENES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,136,279 Severy Apr. 20, 1915 1,476,458 Murray Dec. 4, 1923 1,609,782 Small et al. Dec. 7, 1926 1,721,592 Gattrell July 23, 1929 1,800,946 Mantha Apr. 14, 1931 2,009,191 Buckles July 23, 1935 2,104,658 Langdon Jan. 4, 1938 2,176,897 Fodor -1 Oct. 24, 1939 2,238,574 Thomas et al. Apr.15, 1941 2,296,520 Griswold Sept. 22, 1942 2,309,051 Dodge Jan. 19, 1943 2,321,098 Morse June 8, 1943 2,420,856, Brill et al g-.. May 20, 1947 2,422,596 Stevens June 17, 1947 2,547,038 Parrish Apr. 3, 1951 

